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    Re: Instumental error?
    From: Alexandre Eremenko
    Date: 2005 Apr 21, 00:14 -0500

    In Soviet union we never believed
    any specifications:-)
    (The case we are discussing is even worse:
    My sextant was made in the year SU collapsed:-)
    But I am surprised that you trust so much what
    Celestaire or CP write in their advertising
    booklets. Or is it normal in the West that
    such things are trusted?
    On Thu, 21 Apr 2005, Bill wrote:
    > > Bill wrote:
    > > "> If I recall, the specs
    > >> are plus/minus 10 seconds error along  the arc (0.17').
    > >> Unless you got a
    > >> dud, any value higher than  0.2' is highly suspect.
    > >
    > > And Alex replied:
    > > "Yes, I'm afraid it is a dud."
    > Frank responded:
    > >
    > > I don't buy it. That the certificate *says* the error is 10 seconds doesn't
    > > mean much of anything. Arc error is a correctable error and shooting
    > > lunars/star-star sights is probably the best way to detect it. Build your
    > > table,  and
    > > then use it. And the fact that such error exists doesn't mean the instrument
    > > is a "dud". Correcting for arc error, once you have determined it, is every
    > > bit  as easy as correcting for index error.
    > Frank
    > I was looking at the bigger picture (for a refreshing change of pace).
    > Celestaire, for example, speaks of accuracy by the lot.  I would expect my
    > Atsra III B to be no worse than plus/minus 19" throughout the arc, maybe
    > better, despite any certificate.  Any Cassens & Plath no worse than
    > plus/minus 9".  Any SNO-T no worse than plus/minus 10".  Those should be
    > upper limits.  That is not to say lemons do not exist.
    > I have no cause to believe Soviet military gear would have been substandard
    > (although not petite ;-)  If I accurately recall the post, some sort of cel
    > nav contest was won by a Polish sailor with a SNO-T--a long run of .2'
    > within known positions.  If any of the list members have more details about
    > this seagoing cel-nav superstar, I would love to read them.
    > > I don't buy it.
    > Too bad.  I have a gut feeling Alex would be willing to sell it if the
    > "right" offer came along.   Kidding aside, I believe him to be the sort
    > that will persevere and defeat any idiosyncrasies the SNO-T may posses.
    > Bill

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